Re: 742 to 489 and 741

[Gary Pavlovich <glpavlovich@xxxxxxx>]

I can verify the integrity of the 741 case as Don D. says.  I have been 
running this case in my 340 Dart GT for over eleven years (easy 12's in the 
1/4 mile).  I have a 489 case 3.23 ratio, 489 case 3.73 ratio, 741 case 3.91 
ratio, and a 742 case 4.10 ratio, which is for sale, but I have no qualms 
running all 741 case
Sure Grips in my cars, just so long as they are clutch style.

Gary Pavlovich
----- Original Message ----- 
From: "Don Dulmage" <big-d@xxxxxxxxxxxx>
To: <1962to1965mopars@xxxxxxxxxx>
Sent: Friday, November 16, 2007 8:34 AM
Subject: 742 to 489 and 741


> All have the same size shaft at the spline. The 742 is 1 3/4 at the rear 
> of the pinion by the gear end and the 489 is 1 7/8 the X or 741 is 1 3/8. 
> HOWEVER!!!! (big word aint it. ) they are all the same size where the 
> spline attaches (nut or threaded end of the pinion) and since no piece is 
> stronger than its weakest part the idea that  a 741 or 742 is too weak for 
> serious street use does not wash. The bigger bearing inside increases load 
> carrying abilty by the gear  but in practice the smaller bearing , the 
> front pinion bearing is the one that will fail if you do have any trouble. 
> and it is realitively similar in all three diffs.
> Limited slips (cone and clutch can often be swapped without trouble. 
> Sometimes the carrier bearings are different but with the matching races 
> will fit nicely. I have done this many many times over the years. Axle 
> adjustment or shimming can be tricky sometimes however a green bearing kit 
> makes this detail moot.
> Don
> PS there are two splines often seen in all diffs , at least all 742 and 
> 489s) fine spline and course splines. Often the front seal is the same 
> number as well BTW regardless of the case number
> Author of
> Return to Deutschland (True Adventure)
> Old Reliable (Mopar)
> http://altonapublicschool.faithweb.com/
>
> http://seniordragster.bravehost.com/index.html
> [Non-text portions of this message have been removed]
>
>
> ----
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----
Please address private mail -- mail of interest to only one person -- directly to that person.  I.e., send parts/car transactions and negotiations as well as other personal messages only to the intended recipient, not to the Clubhouse public address. This practice will protect your privacy, reduce the total volume of mail and fine tune the content signal to Mopar topic.  Thanks!

'62 to '65 Mopar Clubhouse Discussion Guidelines:
http://www.1962to1965mopar.ornocar.org/mletiq.html.